The present invention relates to a movable upper tool for a waste-stripping station situated within a machine designed for die-cutting sheet or web-like matter to be converted into packages.
In the course of the production of packages, sheets are fed one by one into a die-cutting press. When the die-cutting operation is accomplished, every sheet has the shape of several cuttings or blanks juxtaposed and attached together with linking points which will be subsequently eliminated, every blank corresponding to a package. However, the blanks do not cover the whole surface of the sheet; in fact, certain areas situated between two blanks or at the periphery of the sheet are waste which have to be removed from the said sheet. For this purpose, every sheet having passed through the die-cutting station is fed individually into a waste-stripping station. This station includes a movable upper tool provided with push-rods, and a lower tool shaped as a perforated plate. With the sheet having been placed on the lower tool so as to undergo the waste-stripping operation, the upper tool is then lowered, thereby allowing the push-rods to press the waste through the corresponding apertures of the perforated plate.
In order to maintain the sheet in position and applied against the perforated plate during the waste-stripping operation, the prior art suggests to fit on the upper tool pressers made out of sponge rubber or similar material.
It is known to make so called universal tools, that is, tools which are able to be adjusted to various arrangements and configurations of the sheet's waste. Such a universal upper tool, as described for example in the Swiss patent CH-A-490943, consists of a horizontal plate with a size at least equivalent to the size of the sheet and perforated with numerous oblong apertures through every one of which a waste portion of the sheet may be pushed in between a push-rod fixed on the lower side of the plate and quick-fitting means arranged on the upper side of the same plate. By choosing the appropriate oblong apertures, and moving the push-rods along the latter apertures, it is possible to adapt the upper tool to every new job with only one plate and an adequate number of push-rods.
Until now, the fitting of the sponge rubber pressers against the lower side of the upper tool has been accomplished with the use of glue. Gluing, though, has the following drawbacks:
destruction of the pressers when removing them; PA1 impossibility of fine adjustment of the position of the presser once in place; and PA1 Necessity to clean the plate.
For this reason, it has been suggested to replace the glue with a double-side adhesive which has nearly the same drawbacks as the glue.